A wide variety of devices have been developed in the past for use in teaching sports skills. In some instances, the devices have included mechanism for limiting body movement. For example, U.S. Pat. No. 3,608,896 shows a device for restraining leg movement in teaching figure ice skating. In other instances, the devices have included strain gauges that determine the force exerted by a particular muscle. One such device is marketed by Integrated Sports Electronics, Inc. under the mark StrokeMaker.
There has been a long standing need for methods and devices for use in teaching sporting skills wherein the device does not interfere with the body movement. Any interference, of course affects the body movement, and thus has limiting effects when used in teaching sporting skills. If a strain gauge is used in teaching tennis, the device itself may change the arm movement of the tennis player. Likewise, a muscular restraint in golf makes the swing unnatural and results in a different feel than is encountered when the device is not present.
Strain gauges are illustrated in U.S. Pat. No. 4,501,148 (Nicholas et. al.). In this instance, the strain gauge is used primarily to measure muscle force. Another such device is illustrated in U.S. Pat. No. 4,103,896 (LaRang). This device provides a gripping mechanism on a golf club to signal excess force when gripping by the off target hand. In another instance, an accelorama curve is provided for measuring acceleration or velocity in the swing, for example, of a bat or golf club. This device is shown in U.S. Pat. No. 3,717,857 (Evans). In each instance, the device adds significantly to the weight and feel of the bat or golf club, and thus produces an unnatural swing feel. The present invention provides a device free of such inherent disadvantages.